Hello
when I was 6 weeks pregnant (4 years ago

), i, too had pains on my left side... .. Ultrasound showed that I had a few nabothean, or water, cysts on my l. Ovary, which was causing the pain. I didn't believe it, because the pain was actually moving up my left side, but when the cysts 'popped', it was a massive sharp pain, and then it was gone.
I hope by now you've reported it to your doc or ob/gyn, and good luck.
Just a note - my ra improved signficantly while I was pregnant.... Today, however it's a different story...
Michelle